5L ■ HUTTONI AN THEORY. 309 



: '^ i\ 



V 



«!i 



1 



ate 



' \i where they traverfe the beds of gneifs and horn- 



of| Ijlend fchiftus, which compofe the main body 



^^^^dif, of the ifland. They are fometimes feveral 



fathoms n thicknefs, obliquely interfering the 

 thefiji; planes of the llrata juft mentioned, which are 

 Ku' pearly vertical. In thefe veins the feltfpar is 



''i 



§ti 



nv 



4t 





r* 



predominant ; it is very highly cryflallized, and 

 conjji of a beautiful flefh colour. Many fmaller veins 



are alfo to be met with in the fame place ; but 

 no large mafs of granite is found, either in this 

 or the adiacent ifland of Tiree. 



275. The Portfoy granite, of which mention 

 has been already made, § 80^ alfo conftitutes a 

 vein or dike, traverfing a highly indurated mica- 

 ■inf^"'" ceous fchiftus, about a mile to the eaftward of 

 liie IL the little town of Portfoy, and not vifibiy con- 

 refp:Cui netted with any large mafs of the fame kind. 

 fpedtsJ; More dikes than one of this granite have been 

 (|ef_ obferved ear the fame fpot. 



aodil 

 tbefs 



iffit 



a 



^i^y A fimilar granite is likewife found inland, 



in the neighbourhood of Huntly, about eigh- 



K 



^., teen miles fouth of Portfoy : but whether in the 

 . , J fhape of a vein or a mafs, I have not been able 

 '^ ' to learn. 



276. Veins of granite are alfo frequent m 

 Cornwall, where they are known by the name 

 9^ lodes, the fame name which is applied in that 

 country to metallic veins. The granite veins fre- 



U 3 quently 



V 



y 



